In general, a cassette tape recorder is an appliance for recording external sound on a tape or reproducing sound recorded on a tape, which has a mode change over device for a user to record external sound on `A` side or on `B` side at the selection of the user as well as to reproduce sound recorded on `A` side or on `B` side at the selection of the user.
As shown in FIG. 1, a conventional mode change over device generally includes a main gear 2 hinged on a main plate 1 for being rotated by the driving force received from a motor (not shown). A pinch gear 3 is hinged on the main plate 1 for being rotated by the driving force received from the main gear 2. A cam gear 4 is hinged on the main plate 1 for being selectively rotated by the driving force received from the pinch gear 3. A solenoid lever 7 is mounted on the main plate 1 with a spring 5 which causes initial engagement of the pinch gear 3 with the cam gear 4. This allows the rotating force of the pinch gear 3 to be transmitted to the cam gear 4 while the solenoid lever 7 is turned along with the movement of the solenoid 6 at change over of a mode. An actuation lever 9 is hinged on the main plate 1 and connected to a first torsion spring 8 for being selectively turned along with the rotation of the cam gear 4. A function plate 10 is movably mounted on the main plate 1 for actuating mode change over switches (not shown) to enable modes of stop, play, record, reverse play, and reverse record while moving in the right and left direction following the turn of the actuation lever 9. A clutch (not shown) is disposed on the shaft of the main gear 2 for transmitting or cutting power upon receipt of the rotating force of the actuation lever 9. A rotation lever 11 is hinged on the main plate 1 and is turned by the driving force received from the solenoid lever 7. A selector (not shown) is disposed on the shaft of the main gear 2 for selective transmission of power to enable FF/REW modes upon receipt of the rotating force of the rotation lever 11. A regulator (not shown) is disposed on the shaft of the pinch gear 3 for regulating the selector upon receipt of the rotating force of the cam gear 4 during selection of modes of play, record, reverse play, and reverse record, and releasing the regulation of the selector on selection of FF/REW modes. And, a power transmitter disposed on the main plate 1 for selective transmission of power to enable driving of a tape upon receipt of rotational force of the main gear 2 through the clutch means and the selection means on selection of modes of play, record, reverse play, reverse record, and FF/REW.
The cam gear 4 includes a upper cam 12 positioned at an upper side thereof, and an inner low cam 13 and an outer low cam 14 each positioned at low side thereof. The upper cam has a first catch projection 12a, a second catch projection 12b, and a third catch projection 12c. The outer low cam 14 has a fist step projection 14a, a second step projection 14b and a third step projection 14c,at one side thereof.
The solenoid lever 7 has a first upper projection pin 7a for selective catch of the first, the second, and the third catch projections 12a, 12b, and 12c of the upper cam 12 upon rotation of the cam gear 4 as well as a first low projection pin 7b for turning the rotation lever 11 upon a turn of the solenoid lever 7. The actuation lever 9 has a second projection pin 9a for engaging the inner low cam 13 of the cam gear 4 as well as a upper recess 9b and a low recess 9c at the upper and low ends thereof. The function plate 10 has a third projection pin 10a for being inserted into the upper recess 9b in the actuation lever 9 at one side of the upper surface thereof.
The clutch has a driving gear 15 integral with the main gear 2 on the under side thereof for being rotated together with the main gear 2. A clutch lever 16 is hinged on the shaft of the main gear 2 for being turned upon receipt of rotating force of the actuation lever 9. And, a movable gear 17 is hinged on the clutch lever 16 at the low end thereof for transmitting power to the power transmitter only upon selection of modes of play, record, reverse play, and reverse record while being rotated by the rotating force of the driving gear 15. The clutch lever 16 has a fourth projection pin 16a at the upper end thereof for inserting into the low recess 9c at the low end of the actuation lever 9, so that, when the actuation lever 9 is turned, the clutch lever 16 is also turned.
The selector has a selection lever 18 hinged on the shaft of the main gear 2 which has a catch piece 18a at the upper end thereof and a projection piece 18b at one side thereof. A selection gear 19 is disposed on the selection lever at the lower end thereof for selective transmission of power to the power transmitter only upon selection of FF/REW modes while being rotated by rotating force of the main gear 2.
The regulator has a regulation lever 21 disposed on the shaft of the pinch gear 3 and engaged with a second torsion spring 20. A contact projection 21a is integral with the regulation lever for turning the regulation lever 21 as it makes contact with the first, the second and the third step projections 14a, 14b, and 14c of the outer low cam 14 formed at under side of the cam gear 4 in sequence on selection of modes of play, record, reverse play and reverse record. And, a catch projection 21b is formed at outer periphery of the regulation lever 21 for catching the selection lever 18 as it is caught by the catch piece 18a formed at the selection lever 18 upon rotation of the regulation lever.
The power transmitter has a first intermediate gear 22 and a second intermediate gear 22a both disposed on the main plate 1 for being rotated at selective reception of rotational force of the selection gear 19 on selection of FF/REW modes. A follower gear 23 is disposed on the main plate 1 for rotating the first intermediate gear 22 by receiving rotation force of the movable gear 17 upon selection of modes of play, record, reverse play and reverse record. A first reel gear 24 is disposed on the main plate 1 for rotating a tape in normal direction while being rotated by the rotating force of the first intermediate gear 22. A second reel gear 24a is also disposed on the main plate 1 for rotating the tape in reverse direction while being rotated by the rotating force of the second intermediate gear 22a.
A device having the foregoing system can change over to a selected mode upon selection of modes play, record, reverse play and reverse record while in a stop condition because of the rotation of the main gear 2 (which also makes the pinch gear 3 rotate). The solenoid 6, which is also actuated, engages with the pinch gear 3 which makes the cam gear 4 rotate. Accordingly, because the solenoid lever 7 turns along the cam path of the upper cam 12 and the actuation lever 9 turns along the cam path of the inner low cam 13, the mode change over switches are actuated.
Operation upon selection of FF/REW modes now explained.
Upon selection of FF mode, the main gear 2 and the driving gear 15 rotate in counter clockwise direction facing the paper upon receipt of rotating force of the motor (not shown). This causes the selection gear 19, hinged at low end of the selection lever 18 and engaged to the main gear 2, to engage the first intermediate gear 22 to rotate the first reel gear 24 in clockwise direction, reeling a tape in normal direction at high speed.
REW mode selection works opposite FF mode selection. After the main gear 2 and the driving gear 15 are rotated, the selection lever 18 turns in clockwise direction about a shaft to cause the selection gear 19 to engage the second intermediate gear 22a and rotate the second reel gear 24a in counter clockwise direction, according to which the tape is reeled in reverse direction at high speed.
The clutch lever 16 also receives rotational force during selection of FF/REW modes, due to the direction of rotation of the main gear 2 and the driving gear 15. However, because the cam gear does not rotate, and the actuation lever 9 which has the low recess 9c formed at the low end of the actuation lever 9 inserted in the fourth projection pin 16a formed at the upper end of the clutch lever 16 remains stationary, the clutch lever 16 can not rotate.
Next, operation in cases when a user selects modes of play, record, reverse play, and reverse record in stop condition shown in FIG. 1(a) when FF/REW mode is only available is to be explained hereinafter.
First, if play or record is selected, the main gear 2 and the driving gear 15 are rotated in clockwise direction, rotating the pinch gear 3 engaged with the main gear 2 in counter clockwise direction. Then, when the solenoid 6 (mounted on the main plate 1) loses magnetic force, the spring 5 pulls the solenoid lever 7, turning the solenoid lever 7 in clockwise direction.
The first upper projection pin 7a, released from the first catch projection 12a pushes on the causing slope the cam gear 4 to rotate about the shaft in clockwise direction facing the paper and engage the pinch gear 3. The cam gear 4 receives the rotating force of the pinch gear continuously, rotates in a clockwise direction, and makes the first projection piece 7b, at the low end of the solenoid lever 7, push one end of the rotation lever 11 hinged on the main plate 1, thus causing it to rotate in a clockwise direction.
This is shown in FIG. 1(b).
Then, as the cam gear 4 continues to turn, the contact projection 21a (formed on the regulation lever 21) makes contact with the first, second, and third step projections 14a, 14b, and 14c of the outer low cam 14 (formed on the under side of the cam gear 4). The regulation lever 21 receives force from the second torsion spring 20 and turns in counter clockwise direction facing the paper about a shaft. Since the solenoid lever 7, turning further in a clockwise direction due to the cam path in the upper cam 12 (formed on the upper side of the cam gear 4), continues to turn the rotation lever 11 in clockwise direction, the other end of the rotation lever 11 in clockwise direction, the other end of the rotation lever pushes the projection piece 18b (formed at one side of the selection lever 18) upward, turning the selection lever 18 in the counter clockwise direction. The regulation lever 21 turns in counter clockwise direction after the selection lever 18 has been turned, and the catch projection 21b (formed on the regulation lever 21) moves until caught by the catch piece 18a (formed at the upper end of the selection lever 18) without being interfered by the catch piece 18a.
The actuation lever 9 (disposed on the main plate 1 and attached to the first torsion spring 8) rotates the clutch lever 16 in counter clockwise direction (while the actuation lever is turned in clockwise direction facing the paper). The second projection piece 9a (formed at one side of the actuation lever 9) is guided in the cam path of the inner low cam 13 following the rotation of the cam gear 4 in clockwise direction. This causes the movable gear 17, hinged on the low end of the clutch lever and engaged with the driving gear 15, to be engaged with the follower gear 23. Thus, when the function plate 10 (having the third projection piece 10a inserted in the upper recess 9b formed at upper side of the actuation lever 9) is moved to the right facing the paper in horizontal direction, a mode change is actuated to make play or record modes available.
Such condition is shown in FIG. 1(c), in which the solenoid lever 7 is caught by the first upper projection pin 7a at the second catch projection 12b of the upper cam 12.
Therefore, the rotational force of the driving gear 15, rotating in clockwise direction together with the main gear 2, is transmitted through the movable gear 17, the follower gear 23, the first intermediate gear 22, and the first reel gear 24 to the reel (not shown). This causes the reel to be rotated in clockwise direction and rotate a tape in normal direction, and play or record is made available according to a selected mode.
At the time of mode change over to play or record condition, as has been explained, even though the selection lever 18 also receives a force tending to turn the selection lever in clockwise direction due to the direction of rotation of the main gear 2 and the driving gear 15, the selection lever 18 can not be rotated due to regulation of the regulation lever 21.
Selection of reverse play mode or reverse record mode is now explained.
Moving the function plate 10 to the right facing the paper in horizontal direction causes the actuation lever 9 to be turned in counter clockwise direction and follow the cam path on the inner low cam 13 (formed under side of the cam gear 4). This actuates the mode change over so that reverse play and reverse record are available. The clutch lever 16, rotates in a clockwise direction and causes the moving gear 17 (hinged on the low end of the clutch lever and engaged with the driving gear 15) to also engage the second intermediate gear 22a. The rotational force of the driving gear 15 is thus transmitted through the movable gear 17, the second intermediate gear 22a, and the second reel gear 24a to the reel. This causes the reel to rotate in a counter clockwise direction, and allows selection of reverse play or reverse record according to a selected mode.
Such a condition is shown in FIG. 1(d), in which the solenoid lever 7 is caught by the first projection piece 7a at the third catch projection 12c of the upper cam 12 formed on the cam gear 4.
In the foregoing operation, turning of the selection lever 18 upon selection of reverse play and reverse record modes is regulated in the same way as when the play and record are selected modes. The force opposite the direction in which the tape is moving, is regulated by preventing the selection lever from being turned in clockwise direction.
The regulation of turning on the selection lever 18 is continued until completion of stop mode on selection of stop mode again in play and record mode conditions or reverse play and reverse record mode conditions. This prevents the tape from excessive transfer during the time period starting at the selection of stop mode and lasting until the motor is completely stopped, because the motor, being unable to stop immediately even after the selection of stop mode, runs more for a certain number of revolutions until the motor comes to a complete stop.
When stop mode is selected again after change over to play, record, reverse play, and reverse record modes as has been explained, all the operations are stopped after coming to a condition shown in FIG. 1(a).
This conventional mode change over device has problems in that the power consumption is increased due to over load of the motor coming from the rotation of gears and shortened life of the device, since, in case of selection of modes of play, record, reverse play, and reverse record in stop condition, the selection gear, hinged on the low end of the selection lever for transmitting power to make FF/REW available, is always receiving rotational force from the main gear.